<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      h1 {
        margin: 0;
        padding: 0;
        color: yellow;
        text-shadow: 3px 3px 1px yellowgreen; /* 水平偏移量：向右；垂直偏移量：向下；模糊半径：越大越模糊 ；阴影基色。*/
      }
    </style>
  </head>
  <body>
    <h1>Hello,world</h1>
  </body>
</html>
